Change method config table to use open addressing with quadratic probing.

pull/8303/head
Mark D. Roth 8 years ago
parent 8e2911adc7
commit 673de79a0e
  1. 59
      src/core/ext/client_config/resolver_result.c

@ -38,7 +38,6 @@
#include <grpc/support/alloc.h>
#include <grpc/support/string_util.h>
#include "src/core/lib/support/murmur_hash.h"
#include "src/core/lib/transport/metadata.h"
/* grpc_addresses */
@ -151,62 +150,60 @@ int32_t* grpc_method_config_get_max_response_message_bytes(
typedef struct method_config_table_entry {
grpc_mdstr *path;
grpc_method_config *method_config;
struct method_config_table_entry *next; // Chaining for collisions.
} method_config_table_entry;
#define METHOD_CONFIG_TABLE_SIZE 30
#define METHOD_CONFIG_TABLE_SIZE 128
typedef struct method_config_table {
method_config_table_entry *entries[METHOD_CONFIG_TABLE_SIZE];
uint32_t hash_seed;
method_config_table_entry entries[METHOD_CONFIG_TABLE_SIZE];
} method_config_table;
static void method_config_table_init(method_config_table* table) {
memset(table, 0, sizeof(*table));
table->hash_seed = (uint32_t)gpr_now(GPR_CLOCK_REALTIME).tv_nsec;
}
static void method_config_table_destroy(method_config_table* table) {
for (size_t i = 0; i < GPR_ARRAY_SIZE(table->entries); ++i) {
method_config_table_entry *entry = table->entries[i];
while (entry != NULL) {
method_config_table_entry *next_entry = entry->next;
method_config_table_entry *entry = &table->entries[i];
if (entry->path != NULL) {
GRPC_MDSTR_UNREF(entry->path);
grpc_method_config_unref(entry->method_config);
gpr_free(entry);
entry = next_entry;
}
}
}
// Helper function for insert and get operations that performs quadratic
// probing (https://en.wikipedia.org/wiki/Quadratic_probing).
static size_t method_config_table_find_index(method_config_table* table,
grpc_mdstr *path,
bool find_empty) {
for (size_t i = 0; i < GPR_ARRAY_SIZE(table->entries); ++i) {
const size_t idx = (path->hash + i * i) % GPR_ARRAY_SIZE(table->entries);
if (table->entries[idx].path == NULL)
return find_empty ? idx : GPR_ARRAY_SIZE(table->entries);
if (table->entries[idx].path == path)
return idx;
}
return GPR_ARRAY_SIZE(table->entries) + 1; // Not found.
}
static void method_config_table_insert(method_config_table* table,
grpc_mdstr *path,
grpc_method_config *config) {
method_config_table_entry *entry = gpr_malloc(sizeof(*entry));
const size_t idx =
method_config_table_find_index(table, path, true /* find_empty */);
// This can happen if the table is full.
GPR_ASSERT(idx != GPR_ARRAY_SIZE(table->entries));
method_config_table_entry *entry = &table->entries[idx];
entry->path = GRPC_MDSTR_REF(path);
entry->method_config = grpc_method_config_ref(config);
entry->next = NULL;
const uint32_t hash = gpr_murmur_hash3(path, sizeof(path), table->hash_seed);
const size_t idx = hash % GPR_ARRAY_SIZE(table->entries);
if (table->entries[idx] == NULL) {
table->entries[idx] = entry;
} else {
method_config_table_entry *last_entry = table->entries[idx];
while (last_entry->next != NULL) {
last_entry = last_entry->next;
}
last_entry->next = entry;
}
}
static grpc_method_config *method_config_table_get(method_config_table* table,
grpc_mdstr *path) {
const uint32_t hash = gpr_murmur_hash3(path, sizeof(path), table->hash_seed);
const size_t idx = hash % GPR_ARRAY_SIZE(table->entries);
for (method_config_table_entry *entry = table->entries[idx];
entry != NULL; entry = entry->next) {
if (entry->path == path) return entry->method_config;
}
return NULL; // Not found.
const size_t idx =
method_config_table_find_index(table, path, false /* find_empty */);
if (idx == GPR_ARRAY_SIZE(table->entries)) return NULL; // Not found.
return table->entries[idx].method_config;
}
/* grpc_resolver_result */

Loading…
Cancel
Save